Make sure you join the local REIN - lot's of good advice/lessons to be learnt there. 

To find a mentor, you can for local Real Estate Investing Associations or meetups in your area.

I'd be hesitant to take this on given the numbers you're talking about, lack of relationships with local contractors and the extensive nature of what needs to be done and what you want to do to add value.

If you haven't tried calling your local RE brokerages and asking for some solid PM recommendations I would do that.

These lenders often have more experience and flexibility with properties that include ADUs and JADUs.Community Banks and Credit Unions: Local community banks and credit unions may be more willing to work with you, especially if they have a better understanding of the local real estate market and the value ADUs and JADUs bring to a property.Mortgage Brokers: A mortgage broker may have access to a wider range of lending options and could help you find a lender willing to consider your property.

All are necessary, honestly we did our direct book site to piggy back off VRBO, air and a local site we use. 90% of it is repeat bookings that like to communicate with us through that direct book site vs some protected site like air.we send out a mass email to all our guests using hostfully email capture and offer 5% off the lowest direct booking price which still nets us more than we get for the same booking through the platforms.we do all of it, direct, local and the platforms, we continue to have good success and our clients/guests love it.as far as the price for the website development- to be honest we had a great year one year and needed a write off so that was a factor as well. bottom line is people find you in so many ways, we don't want to eliminate any of them.

You still need to follow local codes of course.  

It keeps things simple and aligns with the local laws and regulations that directly impact your property.

Thinking local county records possibly? 

Someone local looking for furnished housing is more likely to use Zillow or apartments.com or something like it.